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Introduction

Many efforts have been made to find new and specific “bioactive” additives that promote and accelerate wound healing, regulate inflammation, and improve soft and hard tissue regeneration. The most common are PRP, PRGF and PRF techniques.

The second generation of platelet concentrates – platelet-rich fibrin (PRF) – was subsequently introduced by Joseph Choukroun and his co-workers in 2001. PRF is an autologous biomaterial, made of a very strong fibrin matrix.

PRF protocol achieves the gel consistency without any manipulation of the blood: this method, therefore, totally respects the European directive2004/23/EC, while both the PRP and the PRGF require the addition of biochemical additives in order to be obtained.

Among the advantages that shows to PRF, compared to PRP and PRGF, we can cite a greater simplicity of production and absence of manipulation. Furthermore, the technique of the PRF has the advantage of producing a larger share of blood product over the share of blood taken.

Discussion

PRP

Platelet-rich plasma (PRP) is first generation platelet concentrate aimed to improve tissue repair. Platelet Rich Plasma is a gel at high concentration of autologous platelets suspended in a small amount of plasma after centrifugation of the blood of the patient.  PRP has some significant disadvantages: the preparation protocol is expensive, complicated, and very operator-dependent, and the need for animal thrombin as a coagulant raises legal issues in some countries.

The short duration of cytokine release and its poor mechanical properties have resulted in search of new material.

PRGF

Plasma Rich in Growth Factor (or PRGF) is a type of plasma enriched of proteins and circulating growth factors able to aid the bone and soft tissue regeneration. PRGF contains many different cells and cell-types highly concentrated in a gelatinous form which can be placed into the site of the injury: these cells stimulate and accelerate the healing process by forming blood clots and releasing growth factors into the wound. PRGF does not need bovine or human thrombin for coagulation, however it necessitates Calcium Chloride to be added to PRGF. PRGF includes plasma proteins and coagulative factors and is then more advantageous compared to PRP.

PRF

Platelet Rich Fibrin

The Platelet Rich Fibrin (PRF) is a quite modern, natural platelet concentrate, it is achieved with a simplified preparation, with no biochemical manipulation of bloodThis technique does not require anticoagulants or bovine thrombin (or any other gelling agent). This feature make this product easily usablewith a low rate of mistakes during the preparation stage. The blood taken, approximately 10 ml in tubes without anticoagulant, is immediately centrifuged. The fibrinogen is initially concentrated in the upper part of the tube but, upon the contact with thrombin normally present in the blood, it is converted into fibrin. The platelets are retained into the meshes of fibrin.

Differences among PCs preparation (a) platelet-rich plasma (PRP): after the first centrifugation, the platelet-poor plasma, the ” yellow ” part called buffy coat and a few red blood cells are carefully collected (pipetting) and centrifuged again in order to obtain the PRP (b) PRGF: after centrifugation, the blood is divided in five layers; by pipetting, the undesired parts are discarded; the most concentrated part with growth factors (PRGF) is collected (c) PRF: after centrifugation , a fibrin clot is obtained in the middle of the tube, which is ready to be used

Comparison between the blood products

Although there are some basic similarities between platelet-rich plasma and platelet-rich fibrin, it is the differences between these two products.

Platelet-Rich Fibrin stand out as a superior treatment option.

Both of these products require blood to be taken from the patient. PRP requires more blood to be taken than PRF. Both of the products require the whole blood sample to be placed into a centrifuge, where the blood is then processed to help separate the blood into distinct layers. Platelet-rich plasma is spun at a higher speed, which effectively causes all of the heavier cells in the blood, such as white blood cells and stem cells, to collect in the bottom part of the test tube and allows the lighter platelets and plasma to collect in the top part of the test tube. The platelets and plasma are then collected from the upper part of the test tube and injected into the region with tissue damage.

The PRF product is spun at a lower speed so that the layers of the blood do not separate out as distinctly. This allows some of the white blood cells and stem cells to remain within the platelet layer that is collected for treatment. Thus, there are more healing factors within PRF than is typically seen in PRP. In addition, the lower spin speed causes less trauma to the individual cells of the blood, allowing more stem cells to remain in the final PRF product.

Another distinct difference between platelet-rich plasma and platelet-rich fibrin is the concentration of platelets within the final product.

Platelet-rich fibrin products contain approximately 10 times the platelet concentration that is found within the body.

A final difference worth mentioning between platelet-rich plasma and platelet-rich fibrin is the fact that with PRF, no anticoagulant is used during the processing of the blood. With platelet-rich plasma, the blood that is collected is placed in test tubes that have an anticoagulant called acid citrate dextrose (ACD), which keeps the blood product from clotting too quickly. In an effort to keep the platelet product as natural as possible, the platelet-rich fibrin test tubes do not have any anticoagulant within them.

The PRF has been studied by many research groups, and it has been shown that it is able to stimulate osteogenesis in bone environment, in addition to angiogenesis.

Furthermore, it provides a scaffold consisting of fibrin that allows cellular migration, and these are certainly the fundamental aspects for the process of bone regeneration.

The most important characteristics of the three blood products

One other major difference between the other blood derivatives and the PRF is attributable to the mode of gelification. The PRP and the PRGF need to interact with thrombin and calcium chloride to initiate the last phase of coagulation and fibrin polymerization. These two additives, therefore, influence the speed and mode of gelification, resulting indispensable in the preparation of these products.

Conclusions

The benefit of using the first generation of platelet concentrates was very much debatable and the subject of controversy, but the second generation – PRF – produces more consistent and predictable results. The advantages of using PRF are its autologous nature, simple collection, ease of chair-side preparation, and simple clinical application without the risks associated with allogeneic or animal derived products. The biological properties of PRF clearly show an interesting surgical versatility and all the characteristics that can support faster tissue regeneration and high-quality clinical outcomes.

All these features support the conclusion that the PRF is the best blood productable to better enhance the healing of soft and hard tissue, comparing to other similar blood product.

References:

S. GIANNINI A. CIELO, L. BONANOME, C. RASTELLI, C. DERLA, F. CORPACI, G. FALISIComparison between PRP, PRGF and PRF: lights and shadows in three similar but different protocols

Ana Castro, Nastaran Meschi, Andy Temmerman, Nelson R. Pinto: Regenerative potential of Leucocyte- and Platelet Rich Fibrin (L-PRF). Part A: intrabony defects, furcation defects, and periodontal plastic surgery. A systematic review and meta-analysis

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